import hashlib
import importlib.util
import os
import stat
import typing
from email.utils import formatdate, parsedate
from urllib.parse import quote

import anyio
from fastapi import BackgroundTasks
from starlette.datastructures import URL, Headers
from starlette.exceptions import HTTPException
from starlette.responses import FileResponse, RedirectResponse, Response
from starlette.types import Receive, Scope, Send

PathLike = typing.Union[str, "os.PathLike[str]"]

mimetypes = [
    ("html", "text/html"),
    ("htm", "text/html"),
    ("css", "text/css"),
    ("js", "application/javascript"),
    ("json", "application/json"),
    ("jpg", "image/jpeg"),
    ("jpeg", "image/jpeg"),
    ("png", "image/png"),
    ("gif", "image/gif"),
    ("ico", "image/x-icon"),
    ("svg", "image/svg+xml"),
    ("swf", "application/x-shockwave-flash"),
    ("flv", "video/x-flv"),
    ("mp3", "audio/mpeg"),
    ("mp4", "video/mp4"),
    ("ogg", "application/ogg"),
    ("ogv", "video/ogg"),
    ("wav", "audio/x-wav"),
    ("wma", "audio/x-ms-wma"),
    ("wmv", "video/x-ms-wmv"),
    ("pdf", "application/pdf"),
    ("doc", "application/msword"),
    ("xls", "application/vnd.ms-excel"),
    ("ppt", "application/vnd.ms-powerpoint"),
    ("txt", "text/plain"),
    ("zip", "application/zip"),
    ("rar", "application/x-rar-compressed"),
    ("gz", "application/x-gzip"),
    ("bz2", "application/x-bzip2"),
    ("tar", "application/x-tar"),
    ("bmp", "image/bmp"),
    ("tiff", "image/tiff"),
    ("tif", "image/tiff"),
    ("rtf", "application/rtf"),
    ("xml", "text/xml"),
    ("xsl", "text/xml"),
    ("xsd", "text/xml"),
    ("ttf", "application/x-font-ttf"),
    ("otf", "application/x-font-otf"),
    ("woff", "application/x-font-woff"),
    ("woff2", "application/x-font-woff2"),
    ("eot", "application/vnd.ms-fontobject"),
    ("sfnt", "application/font-sfnt"),
    ("font", "application/font-sfnt"),
    ("cur", "image/vnd.microsoft.icon"),

]


def guess_type(filename: str) -> str:
    for mime in mimetypes:
        if filename.endswith('.'+mime[0]):
            return mime[1]
    return "text/plain"


class NotModifiedResponse(Response):
    NOT_MODIFIED_HEADERS = (
        "cache-control",
        "content-location",
        "date",
        "etag",
        "expires",
        "vary",
    )

    def __init__(self, headers: Headers):
        super().__init__(
            status_code=304,
            headers={
                name: value
                for name, value in headers.items()
                if name in self.NOT_MODIFIED_HEADERS
            },
        )


class Renderer:
    def __init__(
        self,
        *,
        directory: PathLike = None,
        packages: typing.List[str] = None,
        html: bool = False,
        check_dir: bool = True,
    ) -> None:
        self.directory = directory
        self.packages = packages
        self.all_directories = self.get_directories(directory, packages)
        self.html = html
        self.config_checked = False
        if check_dir and directory  is not None and not os.path.isdir(directory):
            raise RuntimeError(f"Directory '{directory}' does not exist")

    def get_directories(
        self, directory: PathLike = None, packages: typing.List[str] = None
    ) -> typing.List[PathLike]:
        """
        Given `directory` and `packages` arguments, return a list of all the
        directories that should be used for serving static files from.
        """
        directories = []
        if directory  is not None:
            directories.append(directory)

        for package in packages or []:
            spec = importlib.util.find_spec(package)
            assert spec  is not None, f"Package {package!r} could not be found."
            assert (
                spec.origin  is not None
            ), f"Directory 'statics' in package {package!r} could not be found."
            package_directory = os.path.normpath(
                os.path.join(spec.origin, "..", "statics")
            )
            assert os.path.isdir(
                package_directory
            ), f"Directory 'statics' in package {package!r} could not be found."
            directories.append(package_directory)

        return directories

    async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
        """
        The ASGI entry point.
        """
        assert scope["type"] == "http"

        if not self.config_checked:
            await self.check_config()
            self.config_checked = True

        path = self.get_path(scope)
        response = await self.get_response(path, scope)
        await response(scope, receive, send)

    def get_path(self, scope: Scope) -> str:
        """
        Given the ASGI scope, return the `path` string to serve up,
        with OS specific path seperators, and any '..', '.' components removed.
        """
        return os.path.normpath(os.path.join(*scope["path"].split("/")))

    async def get_response(self, path: str, scope: Scope) -> Response:
        """
        Returns an HTTP response, given the incoming path, method and request headers.
        """
        if scope["method"] not in ("GET", "HEAD"):
            raise HTTPException(status_code=405)

        try:
            full_path, stat_result = await anyio.to_thread.run_sync(
                self.lookup_path, path
            )
        except PermissionError:
            raise HTTPException(status_code=401)
        except OSError:
            raise

        if stat_result and stat.S_ISREG(stat_result.st_mode):
            # We have a static file to serve.
            return self.file_response(full_path, stat_result, scope)

        elif stat_result and stat.S_ISDIR(stat_result.st_mode) and self.html:
            # We're in HTML mode, and have got a directory URL.
            # Check if we have 'index.html' file to serve.
            index_path = os.path.join(path, "index.html")
            full_path, stat_result = await anyio.to_thread.run_sync(
                self.lookup_path, index_path
            )
            if stat_result  is not None and stat.S_ISREG(stat_result.st_mode):
                if not scope["path"].endswith("/"):
                    # Directory URLs should redirect to always end in "/".
                    url = URL(scope=scope)
                    url = url.replace(path=url.path + "/")
                    return RedirectResponse(url=url)
                return self.file_response(full_path, stat_result, scope)

        if self.html:
            return self.file_response(self.directory+"/index.html", stat_result, scope)
        raise HTTPException(status_code=404)

    def lookup_path(
        self, path: str
    ) -> typing.Tuple[str, typing.Optional[os.stat_result]]:
        for directory in self.all_directories:
            full_path = os.path.realpath(os.path.join(directory, path))
            directory = os.path.realpath(directory)
            if os.path.commonprefix([full_path, directory]) != directory:
                # Don't allow misbehaving clients to break out of the static files
                # directory.
                continue
            try:
                return full_path, os.stat(full_path)
            except (FileNotFoundError, NotADirectoryError):
                continue
        return "", None

    def file_response(
        self,
        full_path: PathLike,
        stat_result: os.stat_result,
        scope: Scope,
        status_code: int = 200,
    ) -> Response:
        method = scope["method"]
        request_headers = Headers(scope=scope)

        response = AutoFileResponse(
            full_path, status_code=status_code, stat_result=stat_result, method=method
        )
        if self.is_not_modified(response.headers, request_headers):
            return NotModifiedResponse(response.headers)
        return response

    async def check_config(self) -> None:
        """
        Perform a one-off configuration check that StaticFiles is actually
        pointed at a directory, so that we can raise loud errors rather than
        just returning 404 responses.
        """
        if self.directory  is None:
            return

        try:
            stat_result = await anyio.to_thread.run_sync(os.stat, self.directory)
        except FileNotFoundError:
            raise RuntimeError(
                f"StaticFiles directory '{self.directory}' does not exist."
            )
        if not (stat.S_ISDIR(stat_result.st_mode) or stat.S_ISLNK(stat_result.st_mode)):
            raise RuntimeError(
                f"StaticFiles path '{self.directory}' is not a directory."
            )

    def is_not_modified(
        self, response_headers: Headers, request_headers: Headers
    ) -> bool:
        """
        Given the request and response headers, return `True` if an HTTP
        "Not Modified" response could be returned instead.
        """
        try:
            if_none_match = request_headers["if-none-match"]
            etag = response_headers["etag"]
            if if_none_match == etag:
                return True
        except KeyError:
            pass

        try:
            if_modified_since = parsedate(request_headers["if-modified-since"])
            last_modified = parsedate(response_headers["last-modified"])
            if (
                if_modified_since  is not None
                and last_modified  is not None
                and if_modified_since >= last_modified
            ):
                return True
        except KeyError:
            pass

        return False


class AutoFileResponse(Response):
    chunk_size = 4096

    def __init__(
        self,
        path: typing.Union[str, "os.PathLike[str]"],
        status_code: int = 200,
        headers: dict = None,
        media_type: str = None,
        background: BackgroundTasks = None,
        filename: str = None,
        stat_result: os.stat_result = None,
        method: str = None,
    ) -> None:
        self.path = path
        self.status_code = status_code
        self.filename = filename
        self.send_header_only = method  is not None and method.upper() == "HEAD"
        if media_type  is None:
            media_type = guess_type(filename or path) or "text/plain"
        self.media_type = media_type
        self.background = background
        self.init_headers(headers)
        if self.filename  is not None:
            content_disposition_filename = quote(self.filename)
            if content_disposition_filename != self.filename:
                content_disposition = "attachment; filename*=utf-8''{}".format(
                    content_disposition_filename
                )
            else:
                content_disposition = f'attachment; filename="{self.filename}"'
            self.headers.setdefault("content-disposition", content_disposition)
        self.stat_result = stat_result
        if stat_result  is not None:
            self.set_stat_headers(stat_result)

    def set_stat_headers(self, stat_result: os.stat_result) -> None:
        content_length = str(stat_result.st_size)
        last_modified = formatdate(stat_result.st_mtime, usegmt=True)
        etag_base = str(stat_result.st_mtime) + "-" + str(stat_result.st_size)
        etag = hashlib.md5(etag_base.encode()).hexdigest()

        self.headers.setdefault("content-length", content_length)
        self.headers.setdefault("last-modified", last_modified)
        self.headers.setdefault("etag", etag)

    async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
        if self.stat_result  is None:
            try:
                stat_result = await anyio.to_thread.run_sync(os.stat, self.path)
                self.set_stat_headers(stat_result)
            except FileNotFoundError:
                raise RuntimeError(f"File at path {self.path} does not exist.")
            else:
                mode = stat_result.st_mode
                if not stat.S_ISREG(mode):
                    raise RuntimeError(
                        f"File at path {self.path} is not a file.")
        await send(
            {
                "type": "http.response.start",
                "status": self.status_code,
                "headers": self.raw_headers,
            }
        )
        if self.send_header_only:
            await send({"type": "http.response.body", "body": b"", "more_body": False})
        else:
            async with await anyio.open_file(self.path, mode="rb") as file:
                more_body = True
                while more_body:
                    chunk = await file.read(self.chunk_size)
                    more_body = len(chunk) == self.chunk_size
                    await send(
                        {
                            "type": "http.response.body",
                            "body": chunk,
                            "more_body": more_body,
                        }
                    )
        if self.background  is not None:
            await self.background()
